There is known in the prosthetic arts myriad devices for replacing the human knee and for approximating its form and function. These prosthetic devices include simple single axis assemblies, single axis assemblies with friction, and various combinations of other features including extension assists, manual locks, automatic locks, and the like. All of these devices may be characterized by the fact that they are designed for only one purpose, and that they must be custom fitted for an individual.
For example, an amputee may be fitted with a prosthetic knee, such as a simple single axis knee. The prosthetic knee socket must be fitted to the individual with great care by a professional prosthetist, and the cost of the prosthetic knee and the professional services may be considerable. However, should the health of the individual improve or deteriorate, or should the agility of the individual change, or should the individual become accustomed to the prosthesis, it may no longer be sufficient for the needs of the wearer.
For example, an individual who learns to walk with proficiency with a simple single axis knee may find that as his or her health deteriorates, a locking knee is more desirable. This problem may be alleviated by the addition of a lock mechanism to the single axis knee, which is known in the art. Prior art prostheses, however, are not adapted easily to be fitted with additional features such as a locking mechanism. Thus the individual must purchase a new prosthesis with the desired features, thereby incurring substantial additional expense. Also, the fitting process must be reiterated, which is also costly.